1. Field of the Invention
The present invention relates to a planar illumination apparatus.
2. Description of the Related Art
A side-light type planar illumination apparatus (backlight) formed by disposing a light source emitting white light along a side end surface of a light guide plate has been widely used as an illumination means for a crystal display panel. Such a planar illumination apparatus is required to achieve thinning, high luminance, uniformity of luminance, and the like, and is increasingly required to improve uniformity of a color tone of emitting light.
However, recently, further reducing color unevenness that is generated on a side opposite to a light source side of a light guide plate becomes an issue along with high resolution of a crystal display panel and thinning/enlargement of the light guide plate. In addition, the planar illumination apparatus is required to partially or locally adjust a color tone on a light guide plate.